In addition to cleaning, another highly desirable characteristic of personal cleanser/shower gel type compositions is to deliver consumer perceivable (e.g., sensory or visual) benefits from the compositions to the skin. One important way of achieving this result is through deposition of benefit agent (e.g., emollient oils and/or of surfactant-insoluble inorganic particles). In turn, this may require incorporation of high levels of such oil or inorganic particles into the cleanser/shower gel composition.
Unfortunately, such dual cleansing and moisturizing compositions are difficult to formulate because cleansing ingredients, in general, tend to be incompatible with moisturizing ingredients. For example, emulsified oil droplets, especially hydrocarbon oil droplets, tend to phase separate from liquids during storage and to form a separate layer at the top of the liquid cleanser.
Also, emollient oils often tend to depress foaming/lathering of cleansing ingredients, especially when the level of surfactants in the liquid cleanser is relatively low (e.g., below about 25% by wt.). However, liquid cleansers containing relatively low level of surfactants and having good lather properties are highly desired because the lower surfactant levels tend to make the composition more mild, to lower cost and to facilitate processing.
Accordingly, there is a need in the art for compositions which contain low level of cleansing ingredients, which are both mild and capable of producing abundant lather, and which also can deliver moisturizing or other active ingredients. In addition, such compositions should stay physically stable at both ambient and elevated storage temperature.
Liquid cleansers, which can deliver skin benefit agents to provide some kind of skin benefit, are known in the art. For example, one method of enhancing delivery of benefit agent to the skin or hair is using cationic polymers such as Polymer JR® from Amerchol or Jaguar® from Rhone Poulenc. This method is disclosed, for example, in U.S. Pat. No. 3,580,853 to Parran et al, U.S. Pat. No. 5,085,857 to Reid et al., U.S. Pat. No. 5,439,682 to Wivell et al; or in WO 94/03152 (assigned to Unilever), WO 92/18100 (assigned to Procter & Gamble) or WO 97/48378 (assigned to Procter & Gamble).
Another method of enhancing delivery of benefit agents to the skin or hair is using large droplets of viscous oils as is described in U.S. Pat. No. 5,661,189 to Grieveson (assigned to Unilever) and U.S. Pat. No. 5,854,293 (assigned to Procter & Gamble).
In addition, the art discloses that physical stability of, for example, an emollient oil cleanser system requires the presence of some sort of suspending or stabilizing agent. U.S. Pat. No. 5,308,526 to Dias et al and U.S. Pat. No. 5,439,682 to Wivell et al, for example, teach the use of crystalline ethylene glycol long chain esters (e.g., ethylene glycol distearate) as suspension agents to prevent the separation of oil droplets from the liquid. There is no disclosure of a water soluble or water swellable starch as a structuring system to provide enhanced stability.
Another type of well-known suspension agents used to stabilize oil droplets in liquid cleansers are high molecular weight, water-soluble polymers such as polyacrylate, modified celluloses and guar polymers as disclosed broadly, for example, in U.S. Pat. No. 5,661,189 to Grieveson et al. and U.S. Pat. No. 5,854,293 to R. W. Glenn, Jr. (assigned to Procter & Gamble). These polymeric stabilizers are also specifically described, for examples, in U.S. Pat. No. 5,905,062 to Elliott et al. (P&G) claiming hydrophobically modified nonionic cellulose for liquid stability, in U.S. Pat. No. 6,172,019 B1 to Dehan et al. (Colgate-Palmolive) using combination of two separate polyacrylic acid polymers and in U.S. Pat. No. 6,001,344 to Villa et al. (Unilever) using the combination of xanthan gum and Carbopol® as a novel structuring system for stable liquid cleansing composition.
Without imparting negative effects on important cleanser properties (such as appearance, lather, in-use/after-use sensory properties and its processability), applicants have found that storage stable liquid cleansers containing emollient oils, fluid or particles, (e.g., 1 to 30% by wt.) can be formulated using a structuring system comprising specific water soluble/or swellable starch of a level higher than 5 wt. % (e.g., about 6 to 30%) in the liquid composition. Using starch structuring system as described in this invention, personal liquid cleansers with non stringy, non lumpy appearance, lotion-like rheology, excellent lather and storage stability can be easily formulated.